Fig. 4: Structural details of the transmembrane domain.
From: Structural basis of proton-coupled potassium transport in the KUP family
a The translocation pathway reveals a tightly sealed extracellular side, a wide-open intracellular tunnel and the putative occluded potassium ion binding site, which is separated from the cytoplasm by a thin gate. The residues lining the intracellular entrance are represented in sticks. The surface representation of the pathway was calculated with HOLLOW52. b Pore radii along the translocation pathway of KimA determined by HOLE53. Features defining the inward-occluded state are highlighted. c Potential potassium ion binding sites within one protomer. d, e Close-up views of the potassium ions and the residues surrounding them with dotted lines showing the distances in Ångstrom. Potassium ions are depicted as purple spheres. f Average minimum distance for each residue to the closest K+ ion over the course of two 135 ns atomistic simulations; errors shown are s.d., individual distances as dot plots, n = 4 repeats. Dashed lines indicate the distances derived from the structural model.
